Data centers can reduce cooling-water use by measuring it consistently, tuning temperature and humidity controls, improving cooling-tower operation, and selecting heat-rejection systems suited to the local climate and water supply. For new builds or major retrofits, closed-loop liquid cooling can avoid evaporative water use in some designs—but liquid cooling alone does not guarantee a water-free facility. Any reduction in on-site water should be weighed against energy use, emissions, and water impacts elsewhere in the supply chain.
Measure water use with a clear boundary
Start by tracking site water use and IT equipment energy over the same reporting period. The U.S. Department of Energy Federal Energy Management Program (DOE FEMP) describes water usage effectiveness (WUE) as annual site water use in liters divided by annual IT equipment energy use in kilowatt-hours. Microsoft describes its WUE metric as water used for humidification and cooling per IT kilowatt-hour. Because the definitions and boundaries may differ, WUE figures from different operators are not directly comparable unless they use the same method.
As an Amazon Associate I earn from qualifying purchases.
Document what the number includes: cooling, humidification, cooling-tower blowdown, and any reclaimed or recycled water. Also distinguish water withdrawn from a source from water consumed, and name the source—such as potable, reclaimed, or recycled water. A WUE value does not show whether a site is in a water-stressed area or capture indirect water impacts associated with electricity generation.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
- Record total site water use and IT energy for matching dates.
- State the WUE definition, included systems, water sources, and reporting period.
- Track local water stress and energy-related water impacts alongside WUE.
Reduce avoidable cooling demand through operations
Review temperature and humidity controls
DOE FEMP recommends checking whether a facility is operating below appropriate temperature set points or controlling humidity more tightly than necessary. Changes should remain within server specifications, reliability requirements, and site operating limits; the recommendation is to assess controls, not to exceed equipment constraints.
Use water-side economizing when conditions allow
A water-side economizer can use an integrated heat exchanger to unload or bypass chillers when outdoor conditions are mild enough. The system configuration affects performance, and the opportunity depends on climate and season; it is not a year-round option at every site.
Improve cooling-tower operation
In a cooling tower, evaporation removes heat and concentrates dissolved minerals in the remaining water. Blowdown removes some concentrated water to manage mineral levels, while makeup water replaces both evaporative and discharged losses. Cycles of concentration describe how concentrated the circulating water is relative to the incoming makeup water.
DOE FEMP says two to four cycles are common and that six or more may be possible, depending on incoming water quality, treatment, and system limits. Its guidance reports that increasing cycles from three to six reduces cooling-tower makeup-water requirements by 20% and blowdown by 50%. The publication date for that figure is not stated on the accessed DOE guidance page, and the result is not a guarantee for every tower.
Operators can monitor conductivity and other water-chemistry measures to manage blowdown and treatment. A cooling-tower water test kit or conductivity meter may support that work, but equipment should be selected with a water-treatment professional and used according to facility specifications.
Rank #3
Choose heat rejection for the site, not one metric
Air-side economizers and dry heat rejection can reduce on-site cooling-water use. Evaporative cooling, in contrast, can use less energy in some conditions while consuming water. Google says its site decisions balance carbon-free energy with responsibly sourced water, including alternatives to freshwater. Its position highlights why a design should be judged across several factors rather than by water use alone.
| Approach | Potential water effect | Important qualification |
|---|---|---|
| Air-side economizing or dry heat rejection | Can reduce on-site cooling-water use | Suitability depends on climate, operating conditions, workload, and facility design. |
| Evaporative cooling and cooling towers | Uses water through evaporation and blowdown | May reduce energy use in some conditions; water chemistry and local supply matter. |
| Water-side economizing | Can reduce chiller operation when conditions permit | Requires suitable heat-exchanger configuration and favorable outdoor conditions. |
| Closed-loop liquid cooling | Can avoid evaporative water use in specified designs | Heat still has to be rejected; the facility’s downstream heat-rejection system determines broader water use. |
For a meaningful comparison, consider site water withdrawal and consumption, WUE under a shared definition, energy use and emissions in the local grid context, seasonal economizer availability, water stress and source, reliability, workload heat density, retrofit complexity, and the complete heat-rejection path. There is no universal best cooling technology established by the available operator and government materials.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Assess closed-loop liquid cooling carefully
Liquid cooling at the chip or rack can move heat through a closed coolant loop to a coolant distribution unit. That does not by itself eliminate facility water use: a DOE schematic shows heat transferring onward to a condenser-water loop and cooling tower. The entire system—including how heat leaves the building and what happens during normal operating conditions—determines the water outcome.
Microsoft says its new designs beginning in August 2024 use closed-loop liquid cooling and that it aims to make zero-water evaporation its primary cooling method across its owned portfolio. In a June 2026 blog, Microsoft described direct-to-chip liquid cooling with zero water evaporation for the cited AI data-center design. These are company design and operating claims for stated scopes, not a guarantee for all data centers or all operating scenarios.
Microsoft also reported nearly 90% improvement in WUE since its first-generation data centers in the early 2000s. This is a company-reported historical comparison, not an independent sector-wide result. In 2025, Microsoft estimated that a new design would avoid 125,000 cubic meters of cooling water annually per facility; that is a company estimate associated with the announced design, not a universal measured saving.
Can a data center use zero water for cooling?
A zero-water claim needs a defined boundary. It may refer to no evaporative cooling water in a particular design, rather than no water used anywhere at the facility or in its electricity supply. Specify the systems covered, water sources counted, and normal operating conditions; separately account for water use in power generation if assessing the broader footprint.
Technology and site conditions determine whether lower on-site water use increases energy demand or emissions. Google has said water cooling can reduce energy use and related carbon emissions compared with air-based cooling in some geographies. That statement and Microsoft’s closed-loop designs address different contexts and do not constitute an apples-to-apples comparison. Google also described a low-water cooling alternative under development in 2022 as having the potential to reduce data-center water use by up to 50%; this was a company-stated potential, not a verified general outcome.
Consider thermal storage only where it fits
Thermal storage can shift cooling production to off-peak or nighttime hours in cool, dry climates. DOE FEMP cautions that water and energy savings may be limited because the approach still relies on mechanical cooling and evaporation, and storage can constrain air-side economizing. Evaluate it against the site’s operating profile rather than treating it as a default water-saving measure.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
